Data traffic in mobile telecommunications networks is continually increasing. Consequently, operators are employing heterogeneous access networks that utilise multiple radio access technologies (RATs) in order to provide greater capacity, particularly in high traffic areas and areas that otherwise have poor network coverage.
Typically, the radio access technologies utilised as part of these heterogeneous access networks include UMTS Radio Access Network (UTRAN) and an Evolved UTRAN (eUTRAN), and Wi-Fi/WLAN. For example, FIG. 1 illustrates schematically a simplified example of a heterogeneous network 1 that comprises a 3GPP RAN 2 and a Wi-Fi RAN 3 suitable for implementing the methods described herein. The 3GPP RAN 2 includes a number of 3GPP radio nodes 4. For example, if the 3GPP RAN was a UTRAN, then these radio nodes would be Node Bs and Radio Network Controllers (RNC). By way of further example, if the 3GPP RAN was an EUTRAN, then these radio nodes would be eNode Bs. The 3GPP RAN 2 is connected to a mobile core network 5. The Wi-Fi RAN 3 includes a number of Wi-Fi/WLAN APs 7 that are connected to a Wi-Fi/WLAN Access Controller (AC) 8. The Wi-Fi/WLAN AC 8 can control each of the Wi-Fi/WLAN APs 7 and implements authentication of a mobile station/user terminal that wants to associate with/attach to the Wi-Fi RAN/WLAN 3.
If the heterogeneous access network comprises a UTRAN, an eUTRAN, and a Wi-Fi RAN/WLAN then both the UTRAN and eUTRAN standards are defined by the 3rd Generation Partnership Project (3GPP), and the relevant 3GPP standards therefore define capabilities for handling load sharing between these 3GPP RANs. In contrast, the Wi-Fi/WLAN standards are defined by the Institute of Electrical and Electronics Engineers (IEEE), and neither the IEEE standards nor the 3GPP standards define capabilities for handling load sharing between Wi-Fi/WLAN and the 3GPP RANs.
In particular, for most currently available devices, i.e. user equipments (UE) or a client device, when the device is within the coverage of both a Wi-Fi RAN/WLAN and a 3GPP RAN, the device will automatically attempt to connect to the Wi-Fi RAN/WLAN and will detach from the 3GPP RAN. Therefore, the decision to move from the 3GPP RAN to the WLAN is made without having considered the load and/or performance of either RAN, and can result in a reduction in performance that is detrimental to both the networks and the user.
In order to provide at least some form of load steering between a Wi-Fi RAN/WLAN and a 3GPP RAN, it is currently being proposed that when a device attempts to associate with the Wi-Fi RAN/WLAN, any relevant conditions of both the WLAN and the 3GPP RAN are evaluated and it is thereby determined whether the device should use the Wi-Fi RAN/WLAN or an available 3GPP RAN. However, as the user equipment identifiers used in the Wi-Fi RAN/WLAN and the 3GPP RAN are different evaluating the relevant conditions of the Wi-Fi RAN/WLAN and the 3GPP RAN is not a simple operation.